1. Field of the Invention
This invention relates generally to valve assemblies for controlling the flow of fluid from a tank and more specifically to the use of such assemblies with a toilet to selectively provide flush volumes of different magnitudes.
2. Description of the Prior Art
In the interest of conserving water, valve assemblies have been disclosed for operation with a toilet tank to provide flush volumes of different magnitudes. Such an apparatus is disclosed by Robinson in U.S. Pat. No. 2,716,242 dated Aug. 30, 1955. In this assembly, a first valve element cooperates with the valve seat associated with an outlet conduit to form a first valve. A second valve is formed by a second valve element which cooperates with a valve seat formed by the first valve element. Both the first and the second valve elements are lighter than an equivalent volume of water and therefore tend to float.
This valve assembly is operable by initially displacing the second valve element to an open position thereby permitting a first volume of the water to flow through the second valve and into the conduit. Since the second valve element is lighter than water, it remains in its open position until it descends with the surface of the water and seats on the second valve seat to inhibit further flow of the water through the second valve. Thus, the magnitude of the first volume of water is dependent upon the height of the second valve seat with respect to the initial height of the fluid in the tank.
To provide a flush with a greater volume of water, the second valve element is displaced beyond its open position to displace the first valve element to an open position displaced from the first valve seat. Fluid in the tank will then flow through the first valve into the conduit. Since the first valve element is lighter than an equal volume of water, it will remain in its open position until it descends with the surface of the water to close the first valve.
This flush valve assembly has not been particularly desirable since there has been no effective means for aligning the first valve element with the first valve seat. As a consequence, the first valve has tended to leak. This, of course, has resulted in a considerable waste of water which defeats the main purpose of a dual volume flush valve assembly. Furthermore, without an effective seat between the first valve element and the first valve seat, the fluid in the tank has not been permitted to accumulate. As a consequence, there has not been sufficient fluid in the tank to provide the next flush.
The difference in the magnitudes of the two flush volumes has been dependent upon the height of the first valve element. In order to significantly reduce the magnitude of the lesser flush volume, the first valve element has been provided with an elongated configuration providing it with a significant height within the flush tank. This elongated configuration has even further hindered the alignment of the first valve element with the first valve seat. The apparatus of the prior art have also been relatively expensive to manufacture so that the cost of the assemblies has been prohibitive for most purposes.